Irrigation systems in general tend to place large amounts of water in areas where they are not needed, thereby drowning plants which, in turn, causes rot. The same system may not provide enough water to other plants which are located, for example, near the top of a hill. On flat ground the water can be evenly distributed but an operator can leave the system on again, causing the undesired flooding.
In U.S. Pat. No. 3,797,253 entitled "Automatic Irrigation System," by Chester C. Rodieck, the present inventor, there is disclosed an automatic system which utilizes a plurality of float activated valves, which valves are connected to a pressurizable water source. An irrigation basin is provided around each item to be watered, with one float activated valve positioned within each basin. One full flow riser of pre-selected height is connected to the exit side of each valve to maintain the float activated valve gate in the closed position once the valve is closed by the float action while allowing water to flow to the next valve through the riser. When the line pressure is turned off, the float activated valve gate falls to its open position ready for another watering cycle. The system disclosed in the referenced patent is extremely effective and fool-proof on relatively level land, but when there is a substantial height differential between adjacent valves, water siphons from the higher valves to the lower valves when the system is turned off. Excessive water is deposited in the basins serviced by the lower valves due to this siphoning action. It therefore would be highly desirable to have a system which would operate as efficiently on sloping ground as the referenced system does on level ground. The present invention directs itself toward the solution of this siphoning problem.